Discrete and free groups acting on locally finite trees

Matthew J. Conder

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arXiv · 2110.10904

Discrete and free groups acting on locally finite trees

Matthew J. Conder

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Abstract

We present an algorithm to decide whether or not a finitely generated subgroup of the isometry group of a locally finite simplicial tree is both discrete and free. The correctness of this algorithm relies on the following conjecture: every `minimal' $n$-tuple of isometries of a simplicial tree either contains an elliptic element or satisfies the hypotheses of the Ping Pong Lemma. We prove this conjecture for $n=2,3$, and show that it implies a generalisation of Ihara's Theorem.

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BibTeX RIS

Matthew J. Conder. 2021-10-21. Discrete and free groups acting on locally finite trees. https://arxiv.org/abs/2110.10904

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